Clinical and experimental research on emotion regulation (ER) has grown tremendously over the past decade. Excessive up- or down-regulation of emotions through emotional avoidance, inhibition, or overcontrol has been implicated in the development and maintenance of emotional disorders in adults, and may also play a role in such disorders in children. Recent evidence points toward emotional dysregulation as a correlate of pain-related stress and negative emotional states. Furthermore, research suggests that effective (and ineffective) modulation of emotions is socialized through various pathways from parents to children. Yet, there is a paucity of research on ER-pain relationships in younger populations. This study will be the first to test for differences in the association between ER and acute laboratory-induced pain responses in children with chronic pain (recurrent headache) (n = 60) and a comparison sample of non- clinical children (n = 60) (aged 8-17 years). Interactions of child ER with sex, child age, and maternal ER will also be examined in these samples. Children and their mothers (N = 240 total) will complete standardized self-report measures of ER and will undergo three previously validated laboratory pain tasks: pressure tolerance, cold pressor, and sensitivity to evoked pressure. Primary hypotheses posit that overall, ER deficits will predict increased pain responsivity across behavioral (tolerance), self-report (pain intensity), cardiovascular (heart rate, blood pressure, cardiac vagal tone), and neuroendocrine (cortisol) pain response domains, and that this ER-pain relationship will be stronger in the chronic pain group. Secondary hypotheses posit a significant relationship between mother and child ER in both samples;this mother-child ER relationship will be moderated by children's sex and age. The current study has the potential to expand our understanding of the emotional processes related to pain, and how maternal ER is linked with these processes in children. The results of this study will help identify ER strategies that potentiate specific domains of the acute pain response in chronic pain and non-clinical children across a range of developmental stages. Results from the proposed study will further our understanding of the complex interactions among psychological, social, and biological factors contributing to pain, and may inform the development of targeted, emotion-regulation-based interventions. Psychological treatment approaches are considered an essential aspect of comprehensive patient care. The study findings have the potential to improve such treatment approaches, thereby dramatically reducing pain-related disability, offsetting future psychological and medical disabilities, and significantly reducing public health costs.